Royalty free music gives users the right to use copyrighted music without having to pay “royalties” for recurring use of the content. In other words, royalty free music allows the buyer to pay for the music license only once and use the music for as long as they want.
Royalty free often gets mistaken for “free” music, which is not the case in many situations. The author or artist who has composed the music decides what kind of license it will have, and therefore, the costs associated.
Public domain refers to all works that are not protected by copyright and can be used without permission or without having to pay the original author/artist. Public domain essentially gives free use of the music in however a user sees fits.
Essentially, that means that content within the public domain can be copied, distributed, interpreted, and displayed in public for free as if they belong to everyone.
A Creative Commons is one of several public copyright licenses that enable the free distribution of an otherwise copyrighted work. At the core of the Creative Commons license is the idea that every CC license ensures licensors get the credit for their work they deserve. It’s a standardized way to grant copyright permissions to their creative work.
In the above websites, you’ll notice that many of the tracks are protected under various Creative Commons licenses. Artists typically upload their work and specify what users would need to provide (attribution-wise) in order to repurpose that work.
Check out the Creative Commons website for complete details on the various types of licenses.
The fair use doctrine allows that excerpts of copyright material may, under certain circumstances, be quoted verbatim for purposes such as criticism, news reporting, teaching, and research, without the need for permission from or payment to the copyright holder.